/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.graphics;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL;
import javax.microedition.khronos.opengles.GL10;
import javax.microedition.khronos.opengles.GL11;
import javax.microedition.khronos.opengles.GL11Ext;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;
import android.opengl.GLUtils;
import android.os.SystemClock;

import com.example.android.apis.R;

public class MatrixPaletteRenderer implements GLSurfaceView.Renderer {
	private Context mContext;
	private Grid mGrid;
	private int mTextureID;

	/**
	 * A grid is a topologically rectangular array of vertices.
	 * 
	 * This grid class is customized for the vertex data required for this
	 * example.
	 * 
	 * The vertex and index data are held in VBO objects because on most GPUs
	 * VBO objects are the fastest way of rendering static vertex and index
	 * data.
	 * 
	 */

	private static class Grid {
		// Size of vertex data elements in bytes:
		final static int FLOAT_SIZE = 4;
		final static int CHAR_SIZE = 2;

		// Vertex structure:
		// float x, y, z;
		// float u, v;
		// float weight0, weight1;
		// byte palette0, palette1, pad0, pad1;

		final static int VERTEX_SIZE = 8 * FLOAT_SIZE;
		final static int VERTEX_TEXTURE_BUFFER_INDEX_OFFSET = 3;
		final static int VERTEX_WEIGHT_BUFFER_INDEX_OFFSET = 5;
		final static int VERTEX_PALETTE_INDEX_OFFSET = 7 * FLOAT_SIZE;

		private int mVertexBufferObjectId;
		private int mElementBufferObjectId;

		// These buffers are used to hold the vertex and index data while
		// constructing the grid. Once createBufferObjects() is called
		// the buffers are nulled out to save memory.

		private ByteBuffer mVertexByteBuffer;
		private FloatBuffer mVertexBuffer;
		private CharBuffer mIndexBuffer;

		private int mW;
		private int mH;
		private int mIndexCount;

		public Grid(int w, int h) {
			if (w < 0 || w >= 65536) {
				throw new IllegalArgumentException("w");
			}
			if (h < 0 || h >= 65536) {
				throw new IllegalArgumentException("h");
			}
			if (w * h >= 65536) {
				throw new IllegalArgumentException("w * h >= 65536");
			}

			mW = w;
			mH = h;
			int size = w * h;

			mVertexByteBuffer = ByteBuffer.allocateDirect(VERTEX_SIZE * size)
					.order(ByteOrder.nativeOrder());
			mVertexBuffer = mVertexByteBuffer.asFloatBuffer();

			int quadW = mW - 1;
			int quadH = mH - 1;
			int quadCount = quadW * quadH;
			int indexCount = quadCount * 6;
			mIndexCount = indexCount;
			mIndexBuffer = ByteBuffer.allocateDirect(CHAR_SIZE * indexCount)
					.order(ByteOrder.nativeOrder()).asCharBuffer();

			/*
			 * Initialize triangle list mesh.
			 * 
			 * [0]-----[ 1] ... | / | | / | | / | [w]-----[w+1] ... | |
			 */

			{
				int i = 0;
				for (int y = 0; y < quadH; y++) {
					for (int x = 0; x < quadW; x++) {
						char a = (char) (y * mW + x);
						char b = (char) (y * mW + x + 1);
						char c = (char) ((y + 1) * mW + x);
						char d = (char) ((y + 1) * mW + x + 1);

						mIndexBuffer.put(i++, a);
						mIndexBuffer.put(i++, c);
						mIndexBuffer.put(i++, b);

						mIndexBuffer.put(i++, b);
						mIndexBuffer.put(i++, c);
						mIndexBuffer.put(i++, d);
					}
				}
			}

		}

		public void set(int i, int j, float x, float y, float z, float u,
				float v, float w0, float w1, int p0, int p1) {
			if (i < 0 || i >= mW) {
				throw new IllegalArgumentException("i");
			}
			if (j < 0 || j >= mH) {
				throw new IllegalArgumentException("j");
			}

			if (w0 + w1 != 1.0f) {
				throw new IllegalArgumentException(
						"Weights must add up to 1.0f");
			}

			int index = mW * j + i;

			mVertexBuffer.position(index * VERTEX_SIZE / FLOAT_SIZE);
			mVertexBuffer.put(x);
			mVertexBuffer.put(y);
			mVertexBuffer.put(z);
			mVertexBuffer.put(u);
			mVertexBuffer.put(v);
			mVertexBuffer.put(w0);
			mVertexBuffer.put(w1);

			mVertexByteBuffer.position(index * VERTEX_SIZE
					+ VERTEX_PALETTE_INDEX_OFFSET);
			mVertexByteBuffer.put((byte) p0);
			mVertexByteBuffer.put((byte) p1);
		}

		public void createBufferObjects(GL gl) {
			// Generate a the vertex and element buffer IDs
			int[] vboIds = new int[2];
			GL11 gl11 = (GL11) gl;
			gl11.glGenBuffers(2, vboIds, 0);
			mVertexBufferObjectId = vboIds[0];
			mElementBufferObjectId = vboIds[1];

			// Upload the vertex data
			gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, mVertexBufferObjectId);
			mVertexByteBuffer.position(0);
			gl11.glBufferData(GL11.GL_ARRAY_BUFFER,
					mVertexByteBuffer.capacity(), mVertexByteBuffer,
					GL11.GL_STATIC_DRAW);

			gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER,
					mElementBufferObjectId);
			mIndexBuffer.position(0);
			gl11.glBufferData(GL11.GL_ELEMENT_ARRAY_BUFFER,
					mIndexBuffer.capacity() * CHAR_SIZE, mIndexBuffer,
					GL11.GL_STATIC_DRAW);

			// We don't need the in-memory data any more
			mVertexBuffer = null;
			mVertexByteBuffer = null;
			mIndexBuffer = null;
		}

		public void draw(GL10 gl) {
			GL11 gl11 = (GL11) gl;
			GL11Ext gl11Ext = (GL11Ext) gl;

			gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

			gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, mVertexBufferObjectId);
			gl11.glVertexPointer(3, GL10.GL_FLOAT, VERTEX_SIZE, 0);
			gl11.glTexCoordPointer(2, GL10.GL_FLOAT, VERTEX_SIZE,
					VERTEX_TEXTURE_BUFFER_INDEX_OFFSET * FLOAT_SIZE);

			gl.glEnableClientState(GL11Ext.GL_MATRIX_INDEX_ARRAY_OES);
			gl.glEnableClientState(GL11Ext.GL_WEIGHT_ARRAY_OES);

			gl11Ext.glWeightPointerOES(2, GL10.GL_FLOAT, VERTEX_SIZE,
					VERTEX_WEIGHT_BUFFER_INDEX_OFFSET * FLOAT_SIZE);
			gl11Ext.glMatrixIndexPointerOES(2, GL10.GL_UNSIGNED_BYTE,
					VERTEX_SIZE, VERTEX_PALETTE_INDEX_OFFSET);

			gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER,
					mElementBufferObjectId);
			gl11.glDrawElements(GL10.GL_TRIANGLES, mIndexCount,
					GL10.GL_UNSIGNED_SHORT, 0);
			gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
			gl.glDisableClientState(GL11Ext.GL_MATRIX_INDEX_ARRAY_OES);
			gl.glDisableClientState(GL11Ext.GL_WEIGHT_ARRAY_OES);
			gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, 0);
			gl11.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER, 0);
		}
	}

	public MatrixPaletteRenderer(Context context) {
		mContext = context;
	}

	public void onSurfaceCreated(GL10 gl, EGLConfig config) {
		/*
		 * By default, OpenGL enables features that improve quality but reduce
		 * performance. One might want to tweak that especially on software
		 * renderer.
		 */
		gl.glDisable(GL10.GL_DITHER);

		/*
		 * Some one-time OpenGL initialization can be made here probably based
		 * on features of this particular context
		 */
		gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);

		gl.glClearColor(.5f, .5f, .5f, 1);
		gl.glShadeModel(GL10.GL_SMOOTH);
		gl.glEnable(GL10.GL_DEPTH_TEST);
		gl.glEnable(GL10.GL_TEXTURE_2D);

		/*
		 * Create our texture. This has to be done each time the surface is
		 * created.
		 */

		int[] textures = new int[1];
		gl.glGenTextures(1, textures, 0);

		mTextureID = textures[0];
		gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);

		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,
				GL10.GL_NEAREST);
		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,
				GL10.GL_LINEAR);

		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
				GL10.GL_CLAMP_TO_EDGE);
		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
				GL10.GL_CLAMP_TO_EDGE);

		gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
				GL10.GL_REPLACE);

		InputStream is = mContext.getResources().openRawResource(R.raw.robot);
		Bitmap bitmap;
		try {
			bitmap = BitmapFactory.decodeStream(is);
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				// Ignore.
			}
		}

		GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
		bitmap.recycle();

		mGrid = generateWeightedGrid(gl);
	}

	public void onDrawFrame(GL10 gl) {
		/*
		 * By default, OpenGL enables features that improve quality but reduce
		 * performance. One might want to tweak that especially on software
		 * renderer.
		 */
		gl.glDisable(GL10.GL_DITHER);

		gl.glTexEnvx(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
				GL10.GL_MODULATE);

		/*
		 * Usually, the first thing one might want to do is to clear the screen.
		 * The most efficient way of doing this is to use glClear().
		 */

		gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

		gl.glEnable(GL10.GL_DEPTH_TEST);

		gl.glEnable(GL10.GL_CULL_FACE);

		/*
		 * Now we're ready to draw some 3D objects
		 */

		gl.glMatrixMode(GL10.GL_MODELVIEW);
		gl.glLoadIdentity();

		GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);

		gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
		gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);

		gl.glActiveTexture(GL10.GL_TEXTURE0);
		gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
		gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
				GL10.GL_REPEAT);
		gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
				GL10.GL_REPEAT);

		long time = SystemClock.uptimeMillis() % 4000L;

		// Rock back and forth
		double animationUnit = ((double) time) / 4000;
		float unitAngle = (float) Math.cos(animationUnit * 2 * Math.PI);
		float angle = unitAngle * 135f;

		gl.glEnable(GL11Ext.GL_MATRIX_PALETTE_OES);
		gl.glMatrixMode(GL11Ext.GL_MATRIX_PALETTE_OES);

		GL11Ext gl11Ext = (GL11Ext) gl;

		// matrix 0: no transformation
		gl11Ext.glCurrentPaletteMatrixOES(0);
		gl11Ext.glLoadPaletteFromModelViewMatrixOES();

		// matrix 1: rotate by "angle"
		gl.glRotatef(angle, 0, 0, 1.0f);

		gl11Ext.glCurrentPaletteMatrixOES(1);
		gl11Ext.glLoadPaletteFromModelViewMatrixOES();

		mGrid.draw(gl);

		gl.glDisable(GL11Ext.GL_MATRIX_PALETTE_OES);
	}

	public void onSurfaceChanged(GL10 gl, int w, int h) {
		gl.glViewport(0, 0, w, h);

		/*
		 * Set our projection matrix. This doesn't have to be done each time we
		 * draw, but usually a new projection needs to be set when the viewport
		 * is resized.
		 */

		float ratio = (float) w / h;
		gl.glMatrixMode(GL10.GL_PROJECTION);
		gl.glLoadIdentity();
		gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
	}

	private Grid generateWeightedGrid(GL gl) {
		final int uSteps = 20;
		final int vSteps = 20;

		float radius = 0.25f;
		float height = 2.0f;
		Grid grid = new Grid(uSteps + 1, vSteps + 1);

		for (int j = 0; j <= vSteps; j++) {
			for (int i = 0; i <= uSteps; i++) {
				double angle = Math.PI * 2 * i / uSteps;
				float x = radius * (float) Math.cos(angle);
				float y = height * ((float) j / vSteps - 0.5f);
				float z = radius * (float) Math.sin(angle);
				float u = -4.0f * (float) i / uSteps;
				float v = -4.0f * (float) j / vSteps;
				float w0 = (float) j / vSteps;
				float w1 = 1.0f - w0;
				grid.set(i, j, x, y, z, u, v, w0, w1, 0, 1);
			}
		}

		grid.createBufferObjects(gl);
		return grid;
	}
}
